Computer Speakers Buyer's Guide
The first step in buying the right printer is to think carefully about your printing requirements. Do you intend have your computer as part of your home theatre setup? Do you want 3D sound in computer games? How loud do you want your system to be? Do you have an unhealthy obsession with bass?
There are quite a few different speaker combinations possible so let's go through the pros and cons for each one.
2.0 Speaker system
This is simply 2 speakers and stereo amplifier. Perfect for music and other basic sound needs. Does'nt take up too much space or clutter your room with wiring. This is also the cheapest option and a good set of stereo speakers can drastically improve your sound quality.
The downside is that you don't get effective surround sound and bass often lacks a lot of clarity and punch.
2.1 computer speakers
Basically the same as above but with an added sub woofer. The sub woofer greatly enhances bass clarity and power. Gunshots and explosions make solid thuds and you'll be surprised at how much you've been missing.
The downside is that the sub woofer costs more money and takes up more space. Also sub woofers tend to be heavy so if you move house a lot you'll save of gym memberships.
4.1 computer speakers
4 speakers and a sub woofer. This really is the optimum setup for surround sound gaming. With 2 speakers positioned behind you games become much more immersible.
The downside's are as always extra cost and space that the speakers take up.
5.1 computer speakers
The 5.1 system adds a front center speaker over the 4.1 system. Generally 5.1 speaker systems are designed for movies and games don't really take advantage of the center channel especially as gamers are usually very close to their front speakers.
If you have the money and you watch DVD's through the system then a 5.1 system makes sense.
6.1 computer speakers
The absolute best setup for surround movies. If your keen on audio and want the best then this is it.
The downside is that you'll not only have to have the amplifier and speakers you'll also need a 6.1 decoder in the form of a Creative Labs Audigy 2 or 6.1 receiver.
Power output

Graph of an amplifiers power output over time
The power output of an amplifier varies over time with loudness changes in the music or movie soundtrack. If you Root Mean Square (RMS) or area under the black line you end up with the average (maximum/realistic) power output, represented by the red line.
Obviously some people like it louder than others so if you live in a small place you won't need the power output of someone who has a large room to fill.
Also if you're going to have a computer based setup you won't be very far from your speakers so you won't need a huge number of watts.
Unfortunately some manufacturer's like to confuse people by quoting power outputs measured in ways other than RMS. If you want to know what RMS power ratings are then have a look at the diagram.
RMS is the only power output rating worth comparing. RMS stands for the root mean square. This would be the area under the line if an amplifiers power was plotted against time. Basically this is the maximum SUSTAINABLE power output of the amplifier. PMPO or burst power output measurements are not accurate since most amplifiers can produce 1000s of watts for a few milliseconds while only the very best can sustain an output of a few 100 watts RMS.